Structural highlights
Function
[CNBL4_ARATH] Acts as a calcium sensor involved in the regulatory pathway for the control of intracellular Na(+) and K(+) homeostasis and salt tolerance. Operates in synergy with CIPK24/SOS2 to activate the plasma membrane Na(+)/H(+) antiporter SOS1. May function as positive regulator of salt stress responses. CBL proteins interact with CIPK serine-threonine protein kinases. Binding of a CBL protein to the regulatory NAF domain of a CIPK protein lead to the activation of the kinase in a calcium-dependent manner.[1] [2] [3]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The Arabidopsis thaliana SOS3 gene encodes a calcium sensor that is required for plant salt tolerance. The SOS3 protein binds to and activates the self-inhibited SOS2 protein kinase, which mediates the expression and activities of various transporters important for ion homeostasis under salt stress. SOS3 belongs to a unique family of calcium-binding proteins that contain two pairs of EF hand motifs with four putative metal-binding sites. We report the crystal structure of a dimeric SOS3 protein in complex with calcium, and with calcium and manganese. Analytical ultracentrifugation experiments and circular dichroism measurements show that calcium binding is responsible for the dimerization of SOS3. This leads to a change in the global shape and surface properties of the protein that may be sufficient to transmit the Ca(2+) signal elicited during salt stress.
The structure of the Arabidopsis thaliana SOS3: molecular mechanism of sensing calcium for salt stress response.,Sanchez-Barrena MJ, Martinez-Ripoll M, Zhu JK, Albert A J Mol Biol. 2005 Feb 4;345(5):1253-64. Epub 2004 Dec 8. PMID:15644219[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ishitani M, Liu J, Halfter U, Kim CS, Shi W, Zhu JK. SOS3 function in plant salt tolerance requires N-myristoylation and calcium binding. Plant Cell. 2000 Sep;12(9):1667-78. PMID:11006339
- ↑ Halfter U, Ishitani M, Zhu JK. The Arabidopsis SOS2 protein kinase physically interacts with and is activated by the calcium-binding protein SOS3. Proc Natl Acad Sci U S A. 2000 Mar 28;97(7):3735-40. PMID:10725350 doi:http://dx.doi.org/10.1073/pnas.040577697
- ↑ Qiu QS, Guo Y, Dietrich MA, Schumaker KS, Zhu JK. Regulation of SOS1, a plasma membrane Na+/H+ exchanger in Arabidopsis thaliana, by SOS2 and SOS3. Proc Natl Acad Sci U S A. 2002 Jun 11;99(12):8436-41. Epub 2002 May 28. PMID:12034882 doi:http://dx.doi.org/10.1073/pnas.122224699
- ↑ Sanchez-Barrena MJ, Martinez-Ripoll M, Zhu JK, Albert A. The structure of the Arabidopsis thaliana SOS3: molecular mechanism of sensing calcium for salt stress response. J Mol Biol. 2005 Feb 4;345(5):1253-64. Epub 2004 Dec 8. PMID:15644219 doi:10.1016/j.jmb.2004.11.025
